Brush holder and manufacturing method thereof

ABSTRACT

A brush holder incorporates a terminal integral part, which has a coupling portion. The coupling portion couples the terminals with each other. The brush holder has a resin body and a plurality of terminals. The resin body has an opening. The terminals are embedded in the resin body. The terminals are coupled to each other by the coupling portion as an integral part before being embedded in the resin body. The coupling portion is exposed from the opening of the resin body. The terminals are separated from each other by cutting the coupling portion, which is exposed from the opening of the resin body. A coating member coats the opening of the resin body to insulate each terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of pending U.S. Patent Application,entitled “Brush Holder And Manufacturing Method Thereof”, Ser. No.10/393,669, filed on Mar. 19, 2003.

BACKGROUND OF THE INVENTION

The present invention relates to a brush holder used for a motor and amanufacturing method of the brush holder.

A conventional brush holder is located inside a motor housing andincludes a main body, which retains brushes, and a connector portion,which is integrally formed with the main body. The connector portion isexposed from the motor housing and is electrically connected to anexternal device. Terminals are embedded in the brush holder and extendfrom the connector portion to the main body of the brush holder.

The terminals include a first terminal, which receives power supply fromthe outside, and a second terminal, which sends out detection signals ofa detector to the outside. The detector includes, for example, arotation sensor, which detects rotational speed of the motor. The firstand second terminals are apart from each other at a predeterminedinterval at the main body and the connector. In other words, the firstand second terminals are insulated from each other.

The brush holder is formed of resin by injection molding. Morespecifically, resin is filled in a mold, with the first and secondterminals placed in the mold, to form the brush holder.

In a case when the brush holder is molded with separate terminals placedin the mold, the procedure for placing the terminals in the mold iscomplicated. Therefore, in the conventional brush holder, a unit inwhich the terminals are coupled to each other at predetermined portionsis placed in the mold. Then, resin is filled in the mold to form thebrush holder. After that, the coupling portions between the terminalsare cut.

The cut portions of the terminals are exposed from the brush holder.Therefore, liquid could enter from the exposed portion. Further, if anyof the cut portions is in the vicinity of the brushes, foreign objects(such as brush powder scattered from the brushes) could enter from theexposed portion and cause a short-circuit at the cut portion of theterminals.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide abrush holder that reliably prevents short-circuit of terminals and amanufacturing method of the brush holder.

To achieve the above objective, the present invention provides amanufacturing method for a brush holder. The brush holder is locatedinside a motor housing and retains a brush. The method includes: forminga terminal integral part, which includes a plurality of terminals and acoupling portion, wherein the coupling portion couples the terminalswith each other; molding a resin body to embed the terminal integralpart, wherein the resin body forms at least part of the brush holder andhas an opening from which the coupling portion is exposed; separatingthe terminals from each other by cutting the coupling portion, which isexposed from the opening of the resin body; and coating the opening ofthe resin body with a coating member to insulate the separated terminalsfrom each other.

The present invention also provides a brush holder. The brush holder islocated inside the motor housing and retains a brush. The brush holderincorporates a terminal integral part, which has a coupling portion. Thecoupling portion is located at a predetermined position and couples theterminals with each other. The brush holder has a resin body, aplurality of terminals and a coating member. The resin body forms atleast part of the brush holder. The resin body has an opening. Theterminals embedded in the resin body. The terminals are coupled to eachother by the coupling portion as an integral part before being embeddedin the resin body. The coupling portion is exposed from the opening ofthe resin body. The terminals are separated from each other by cuttingthe coupling portion, which is exposed from the opening of the resinbody. The coating member coats the opening of the resin body to insulateeach terminal.

Other aspects and advantages of the invention will become apparent fromthe following description, taken in conjunction with the accompanyingdrawings, illustrating by way of example the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best beunderstood by reference to the following description of the presentlypreferred embodiments together with the accompanying drawings in which:

FIG. 1 is a cross-sectional view illustrating a motor according to afirst embodiment of the present invention;

FIG. 2 is a partial cross-sectional view illustrating the motor shown inFIG. 1;

FIG. 3 is a view illustrating the brush holder of the motor in FIG. 1from the direction indicated by an arrow A in FIG. 2;

FIG. 4 is a view illustrating the terminals located inside the brushholder shown in FIG. 3;

FIG. 5 is a view illustrating a resin body, which forms the brush foldershown in FIG. 3;

FIG. 6 is a view illustrating an integral part of the terminals of thebrush holder shown in FIG. 3;

FIG. 7 is a partial cross-sectional view illustrating a modifiedembodiment of the motor;

FIG. 8 is a view illustrating the brush holder of the modifiedembodiment of the motor shown in FIG. 7;

FIG. 9 is another view illustrating the brush holder shown in FIG. 8;

FIG. 10 is still another view illustrating the brush holder shown inFIG. 8; and

FIG. 11 is a view illustrating the sealing member of the modifiedembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the present invention will now be describedwith reference to FIGS. 1 to 6.

FIG. 1 shows a motor 1 of the preferred embodiment. The motor 1 is usedfor a power source of a power window system installed in a vehicle. Themotor 1 includes a motor main body 2 and a reduction mechanism, which isa reduction gear 3.

The motor main body 2 includes a yoke housing member 4, which forms partof a motor housing, a pair of magnets 5, armature 6, a brush holder 7,and a pair of brushes 8.

The yoke housing member 4 is an inverted cup-shaped member. The pair ofmagnets 5 is secured to the inner circumferential surface of the yokehousing member 4. The armature 6 is rotatably accommodated inside theyoke housing member 4 radially inward of the magnets 5. The armature 6has a rotary shaft 9. The proximal end of the rotary shaft 9 isrotatably supported by a bearing 10, which is attached to the center ofthe ceiling of the yoke housing member 4.

The yoke housing member 4 has an opening portion 4 a. A pair of flanges4 b extends radially outward from the opening portion 4 a. The yokehousing member 4 is secured to a gear housing member 21, which will bedescribed later, by the flanges 4 b and bolts 11.

The brush holder 7 is held between the flanges 4 b of the yoke housingmember 4 and an opening portion 21 a of the gear housing member 21 (seeFIGS. 2 and 3).

The brush holder 7 has a holder main body 7 a, an extended portion 7 b,and a connector portion 7 c. The holder main body 7 a substantiallycloses the opening portion 4 a of the yoke housing member 4. Theextended portion 7 b extends radially outward from the holder main body7 a. The connector portion 7 c is exposed outside the motor 1 from theextended portion 7 b, and is electrically connected to an outsidedevice.

A clamping portion 7 d, which is connected to the extended portion 7 b,is located around the outer circumferential portion of the holder mainbody 7 a. The clamping portion 7 d is held between the flanges 4 b ofthe yoke housing member 4 and the opening portion 21 a of the gearhousing member 21 with the extended portion 7 b.

A bearing 12 is attached to the substantial center of the holder mainbody 7 a. The bearing 12 rotatably supports a predetermined portion ofthe distal end of the rotary shaft 9. A brush retainer 7 e is formed onthe holder main body 7 a to retain the brushes 8. The brushes 8 slideagainst a commutator 13. The commutator 13 rotates integrally with therotary shaft 9.

An accommodating recess 7 f is formed in the holder main body 7 a. Asubstrate 14 is attached to the accommodating recess 7 f. The substrate14 includes a pair of magnetometric sensors 15, which have hallelements. A rotary body 24 a of a clutch 24, which will be describedlater, is coupled to the distal end of the rotary shaft 9 and rotatesintegrally with the rotary shaft 9. An annular sensor magnet 16 issecured to the rotary body 24 a. The sensor magnet 16 is multipolarisedin the circumferential direction. The sensor magnet 16 rotatesintegrally with the rotary shaft 9. The magnetometric sensors 15 detectinformation (such as the number of revolutions and the rotational speed)based on variation of the magnetic field of the sensor magnet 16, whichrotates integrally with the rotary shaft 9.

As shown in FIGS. 3 and 4, six terminals 17 are embedded in the holdermain body 7 a, the extended portion 7 b, and the connector portion 7 cof the brush holder 7. Two of the terminals 17 are first terminals 17 aused for power supply and the other four terminals 17 are secondterminals 17 b used for sending out signals. The first terminals 17 areceive power supply from the outside, which then supply the power tothe brushes 8. The second terminals 17 b send out detection signals fromthe substrate 14 to the outside.

The first terminals 17 a extend from the connector portion 7 c to apredetermined position of the holder main body 7 a via the extendedportion 7 b. The first terminals 17 a are connected to the brushes 8.The entire widths of the first terminals 17 a are substantially thesame. The second terminals 17 b extend from the connector portion 7 c toa predetermined position of the holder main body 7 a via the extendedportion 7 b. The second terminals 17 b are connected to the substrate14. The widths of portions of the second terminals 17 b that are exposedinside an opening 7 g of the connector portion 7 c are the same as thewidths of the first terminals 17 a. The widths of other portions of thesecond terminals 17 b that are embedded in the brush holder 7 arenarrower than the widths of the first terminals 17 a. The first andsecond terminals 17 a, 17 b are located substantially parallel to eachother at predetermined intervals and insulated from each other.

The clamping portion 7 d, the extended portion 7 b, and the connectorportion 7 c of the brush holder 7 are coated by a sealing member 18. Thesealing member 18 is formed of elastomer, which is elastic andinsulative. The sealing member 18 is sandwiched between the openingportion 4 a of the yoke housing member 4 and the opening portion 21 a ofthe gear housing member 21 to hermetically seal the opening portions 4 aand 21 a. The sealing member 18 prevents foreign objects, such as liquidand dust, from entering the yoke housing member 4 and the gear housingmember 21. The sealing member 18 also prevents foreign objects fromentering the opening 7 g of the connector portion 7 c.

The reduction gear 3 shown in FIG. 1 includes the gear housing member21, which forms part of the motor housing, a worm shaft 22, a worm wheel23, and the clutch 24. The gear housing member 21 is made of resin andhouses the worm shaft 22, the worm wheel 23, and the clutch 24. The gearhousing member 21 has the opening portion 21 a, which faces the openingportion 4 a of the yoke housing member 4. The gear housing member 21 andthe yoke housing member 4 are secured to each other by the bolts 11 withthe brush holder 7 sandwiched in between.

The worm shaft 22 is rotatably supported by bearings 25, 26 located atpredetermined positions inside the gear housing member 21. The wormshaft 22 is coupled to the rotary shaft 9, which extends from the motormain body 2, via the clutch 24. The clutch 24 transmits drive force ofthe rotary shaft 9 to the worm shaft 22 and locks rotation of the wormshaft 22 to prevent drive force from being transmitted from the wormshaft 22 to the rotary shaft 9.

The worm shaft 22 is meshed with the worm wheel 23. The worm wheel 23 iscoupled to an output shaft 27, which is located perpendicular to theaxial direction of the worm shaft 22. The output shaft 27 is coupled toan X-arm window regulator (not shown), which selectively opens andcloses a window glass (not shown). When the output shaft 27 is rotated,the window regulator is activated to selectively open and close thewindow glass.

The brush holder 7 according to the preferred embodiment used in themotor 1 is manufactured as follows.

At first, a terminal integral part 30, which includes the first andsecond terminals 17 a, 17 b as one unit as shown in FIG. 6, is placedinside a first mold (not shown), which is used for molding the brushholder 7. The terminal integral part 30 includes first connectingportions 30 a and second connecting portions 30 b. The first connectingportions 30 a connect the second terminals 17 b with each other at aproximal end 7 h of the connector portion 7 c. The second connectingportions 30 b connect the first and second terminals 17 a, 17 b witheach other at the extended portion 7 b of the connector portion 7 c. Theterminal integral part 30 is formed by punching a plate-like member,which is not shown, and folding the plate-like member into apredetermined shape.

Then, resin is poured into the first mold in which the terminal integralpart 30 is placed. As shown in FIG. 5, a resin body 31, which formssubstantially the entire brush holder 7 (that is, substantially theentire portion of the holder main body 7 a, the clamping portion 7 d,the extended portion 7 b, and the connector portion 7 c), is formed.First openings 31 a and a second opening 31 b are formed in the resinbody 31. The first connecting portions 30 a of the terminal integralpart 30 are exposed from the first openings 31 a, and all the secondconnecting portions 30 b are exposed from the second opening 31 b.

The resin body 31, which forms the brush holder 7, is removed from thefirst mold. A tool (not shown) is inserted from each of the first andsecond openings 31 a, 31 b of the resin body 31 to cut the correspondingfirst or second connecting portions 30 a, 30 b of the terminal integralpart 30 (see FIG. 4). The second connecting portions 30 b are cut by atool simultaneously. The first and second terminals 17 a, 17 b areseparated and insulated from each other.

The resin body 31 is placed inside a second mold (not shown) to mold thesealing member 18 from elastomer onto the resin body 31. Elastomer ispoured into the second mold to form the sealing member 18 integrallywith the resin body 31, which forms the clamping portion 7 d of thebrush holder 7, the extended portion 7 b, and the connector portion 7 c.Elastomer, which forms the sealing member 18, is simultaneously filledin the first openings 31 a located at the proximal end 7 h of theconnector portion 7 c and the second opening 31 b of the extendedportion 7 b. This forms terminal coating members 18 a, which coat thefirst terminals 17 a, and a terminal coating member 18 b, which coatsthe second terminals 17 b (see FIGS. 2 and 3). Each terminal coatingmember 18 a or 18 b prevents the corresponding first or second terminals17 a, 17 b from being exposed from the corresponding first or secondopening 31 a, 31 b. This prevents foreign objects, such as liquid ordust, from entering inside the first and second openings 31 a, 31 b.Thus, each first or second terminal 17 a, 17 b is prevented from beingshort-circuited.

The terminal coating member 18 b, which fills the second opening 31 b ofthe extended portion 7 b, is sandwiched between the left side flange 4 b(as viewed in FIG. 2) of the yoke housing member 4 and part of the gearhousing member 21. Therefore, the terminal coating member 18 b isreliably prevented from falling off.

The preferred embodiment provides the following advantages.

The terminal coating members 18 a, 18 b are formed to coat the first andsecond openings 31 a, 31 b of the resin body 31. Therefore, the terminalcoating members 18 a, 18 b reliably prevent foreign objects fromentering the first and second openings 31 a, 31 b where the first andsecond terminals 17 a, 17 b are exposed. Therefore, the first and secondterminals 17 a, 17 b are reliably prevented from being short-circuitedby foreign objects.

The terminal coating members 18 a, 18 b are integrally formed with thebrush holder 7 and closely contact the opening portion 4 a of the yokehousing member 4 and the opening portion 21 a of the gear housing member21. The terminal coating members 18 a, 18 b are formed of the samematerial as the sealing member 18, which seals the opening portions 4 a,21 a. Therefore, the number of materials that form the brush holder 7does not increase. Also, the terminal coating members 18 a, 18 b and thesealing member 18 can be made at the same time if the materials are thesame.

The first and second connecting portions 30 a, 30 b of the terminalintegral part 30 are formed at the extended portion 7 b and theconnector portion 7 c. In other words, the first and second openings 31a, 31 b need not be formed in the holder main body 7 a to cut the firstand second connecting portions 30 a, 30 b. Therefore, a space forarranging several components including the brushes 8 is reliablyobtained in the holder main body 7 a. This increases the flexibility ofdesigning the brush holder 7.

The first and second connecting portions 30 a, 30 b of the terminalintegral part 30 are located on at least two portions, which are theextended portion 7 b and the connector portion 7 c. Therefore, the firstand second terminals 17 a, 17 b of the terminal integral part 30 areprevented from moving independently. This facilitates handling of theterminal integral part 30.

The second connecting portions 30 b are cut with a tool at once. Thisfacilitates cutting of the second connecting portions 30 b.

The second opening 31 b of the resin body 31 of the brush holder 7 andthe terminal coating member 18 b, which coats the second opening 31 b,are arranged to be sandwiched between the yoke housing member 4 and thegear housing member 21. Therefore, the terminal coating member 18 b isreliably prevented from falling off. Thus, foreign objects are morereliably prevented from entering the second opening 31 b.

It should be apparent to those skilled in the art that the presentinvention may be embodied in many other specific forms without departingfrom the spirit or scope of the invention. Particularly, it should beunderstood that the invention may be embodied in the following forms.

The first and second connecting portions 30 a, 30 b of the terminalintegral part 30 may be located at only one of the holder main body 7 a,the extended portion 7 b, and the connector portion 7 c.

In the preferred embodiment, the first and second connecting portions 30a, 30 b are located at the extended portion 7 b and the connectorportion 7 c. However, the first and second connecting portions 30 a, 30b may be located at any two of the holder main body 7 a, the extendedportion 7 b, and the connector portion 7 c.

The terminal coating members 18 a, 18 b, and the sealing member 18 maybe made of different material. The terminal coating members 18 a, 18 b,and the sealing member 18 need not be formed simultaneously. Theterminal coating members 18 a, 18 b may be made of elastic materialother than elastomer, or material other than elastic material.

The structure of the brush holder 7 may be modified as required. Themanufacturing procedure of the brush holder 7 may also be changed asrequired.

The sealing member 18 may be formed separately from the resin body 31.That is, a molded sealing member may be attached to a resin bodyafterwards (see FIGS. 7 to 11).

FIGS. 7 and 8 show a brush holder 35. As in the preferred embodiment ofFIGS. 1 to 6, the brush holder 35 includes a holder main body 35 a, anextended portion 35 b, and a connector portion 35 c. The holder mainbody 35 a substantially closes the opening portion 4 a of the yokehousing member 4. The extended portion 35 b extends radially outwardfrom the holder main body 35 a. The connector portion 35 c is exposedoutside the motor 1 from the extended portion 35 b, and is electricallyconnected to an outside device. A clamping portion 35 d is locatedaround the outer circumferential portion of the holder main body 35 a.The clamping portion 35 d extends from the extended portion 35 b. Theclamping portion 35 d is sandwiched between the flanges 4 b of the yokehousing member 4 and the opening portion 21 a of the gear housing member21 with the extended portion 35 b.

Two first terminals 36 used for power supply are embedded in the holdermain body 35 a, the extended portion 35 b, and the connector portion 35c of the brush holder 35 as shown in FIG. 8. The first terminals 36extend from the connector portion 35 c to a predetermined position ofthe holder main body 35 a via the extended portion 35 b, and areconnected to brushes, which are not shown.

The brush holder 35 includes a resin body 40. As shown in FIG. 9, theresin body 40 is formed by insert-molding a terminal integral part 41.The terminal integral part 41 includes the first terminals 36, which areconnected to each other by a connecting portion 41 a. FIG. 8 shows acompleted state of the brush holder 7. FIG. 9 shows a state before firstand second sealing members 37, 38 are attached to the brush holder 7 andbefore the connecting portion 41 a is cut. An engaging hole 40 a, whichexposes the connecting portion 41 a of the terminal integral part 41, isformed in the extended portion 35 b of the resin body 40. After theresin body 40 is molded, a tool (not shown) is inserted from theengaging hole 40 a to cut the connecting portion 41 a. Thus, the firstterminals 36 are insulated from each other.

The pair of first and second sealing members 37, 38 is attached to theclamping portion 35 d and the extended portion 35 b of the brush holder35 as shown in FIGS. 10 and 11. The first and second sealing members 37,38 are molded from elastomer, which is elastic and insulative,separately from the resin body 40. The first sealing member 37 closelycontacts the opening portion 4 a of the yoke housing member 4, and thesecond sealing member 38 closely contacts the opening portion 21 a ofthe gear housing member 21. The first and second sealing members 37, 38are sandwiched between the yoke housing member 4 and the gear housingmember 21 so that the openings 4 a, 21 a are hermitically sealed. Thisprevents foreign objects, such as liquid and dust, from entering theyoke housing member 4 and the gear housing member 21.

The first and second sealing members 37, 38 have terminal coatingmembers 37 a, 38 a, which hermetically seal the engaging hole 40 a andprevent foreign objects from entering the engaging hole 40 a. Thisprevents the first terminals 36 from causing short-circuit. Projections37 b, 38 b are formed on the terminal coating members 37 a, 38 a,respectively. The projections 37 b, 38 b fit with both openings of theengaging hole 40 a. The projections 37 b, 38 b may be omitted. Theterminal coating members 37 a, 38 a are sandwiched between the left sideflange 4 b of the yoke housing member 4 and part of the gear housingmember 21 as shown in FIG. 7. Therefore, the terminal coating members 37a, 38 a are reliably prevented from falling off. Although the sealingmembers 37, 38 are attached to the resin body 40 as in the modifiedembodiment, the same advantages as the preferred embodiment shown inFIGS. 1 to 6 are provided.

The structure of the motor 1 may be changed as required. For example,the motor 1 may only include the motor main body 2, and the reductiongear 3 may be omitted. Also, a substrate that forms a control circuitfor controlling the motor 1 may be provided.

Therefore, the present examples and embodiments are to be considered asillustrative and not restrictive and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalence of the appended claims.

1-12. (canceled)
 13. A brush holder, which is attached to the motorhousing to close an opening of the motor housing and retains a brush,the brush holder comprising: a resin body forming at least part of thebrush holder, wherein the resin body has an opening; a plurality ofterminals embedded in the resin body, wherein the terminals are coupledto each other by a coupling portion so as to form an integral partbefore being embedded in the resin body, wherein the coupling portion isexposed from the opening of the resin body, and wherein the terminalsare separated from each other by cutting the coupling portion, which isexposed from the opening of the resin body; a sealing member provided onthe resin body, the sealing member sealing the opening of the motorhousing when the brush holder is attached to the motor housing; and acoating member for insulating the separated terminals from each other,wherein part of a material of the sealing member fills the opening ofthe resin body to form the coating member.
 14. The brush holderaccording to claim 13, wherein the sealing member is molded integrallywith the resin body.
 15. (canceled)
 16. (canceled)
 17. (canceled) 18.The brush holder according to claim 13, wherein the sealing member isformed of elastic material.
 19. The brush holder according to claim 18,wherein the elastic material is elastomer.
 20. The brush holderaccording to claim 13, further comprising a main body, which is locatedinside the motor housing and retains the brush, an extended portion,which extends from the main body to the outside of the motor housing,and a connector portion, which is exposed outside the motor housing fromthe extended portion, wherein the coupling portion is located at aposition corresponding to at least one of the extended portion and theconnector portion.
 21. The brush holder according to claim 13, furthercomprising a main body, which is located inside the motor housingretains the brush, an extended portion, which extends from the main bodyto the outside of the motor housing, and a connector portion, which isexposed outside the motor housing from the extended portion, wherein thecoupling portion is one of coupling portions located at positionsassociated with at least two of the positions corresponding to the mainbody, the extended portion, and the connector portion.
 22. The brushholder according to claim 13, wherein the coupling portion is one of aplurality of coupling portions, and wherein the coupling portions areexposed from the opening of the resin body.
 23. The brush holderaccording to claim 22, wherein the coupling portions are cut at once.24. The brush holder according to claim 13, wherein the motor housingincludes a yoke housing and a gear housing, wherein the yoke housingforms part of a motor main body, which rotates a rotary shaft, whereinthe gear housing accommodates a reduction mechanism, which is assembledto the yoke housing and reduces rotation of the rotary shaft, whereinthe brush holder is held and fixed between the yoke housing and the gearhousing, and wherein the opening of the resin body and the coatingmember are located at a portion of the brush holder, which is heldbetween the yoke housing and the gear housing.